UPDATE and INSERT statements with Doctrine DBAL and MySQL JSON type

JsonObject.php

<?php

class JsonObject
{
    /** @var string $result */
    private $result;

    private function __construct(string $result)
    {
        $this->result = $result;
    }

    /**
     * @param array $array
     * @return JsonObject
     * @see https://elephantdolphin.blogspot.com/2016/02/mysqls-json-functions-verses-phps-json.html
     */
    public static function fromArray(array $array): JsonObject
    {
        $result = "";
        foreach ($array as $key => $value) {
            $result .= "'$key', '$value', ";
        }

        return new self(substr($result,0,(strlen($result) - 2)));
    }

    /**
     * @return string
     */
    public function getResult(): string
    {
        return $this->result;
    }
}

statements.php

<?php

// Initial INSERT
$data = ['foo' => json_encode($foo->toArray())];
$dbal->connection->insert('foos', $data);

// Convert array to JSON Object
$newData = $newFoo->toArray());
$object = JsonObject::fromArray($newData);

// UPDATE
$stmt = $dbal->connection->prepare(sprintf(
    "UPDATE `foos` SET
    foo = JSON_ARRAY_APPEND(foo, '$', JSON_OBJECT(%s))
    WHERE foo_id = :fooId", $object
));
$stmt->bindValue('fooId', $data['fooId']);
$stmt->execute();

The original method was taken from here by @mysqlmentor:

• https://elephantdolphin.blogspot.com/2016/02/mysqls-json-functions-verses-phps-json.html

The method works fine as long as I am using strings only.
For more complex use cases I guess I will add a toJsonObject custom method on my read/view models.

Here is an improved version of the method by @adelineu:

• https://gist.github.com/adelineu/61bbae9ca079ccd3a9e95d6b2755879a